All language subtitles for Secrets of our Living Planet 3of4 The Magical Forest 720p HDTV x264 AAC MVGroup org_Subtitles01.ENG

Ten million species live on
planet earth.

Each one is remarkable.

But none can survive on its own.

All life depends upon connections.

Unexpected, invariably complex,
beautiful relationships between
millions of plants and animals.

This time, in our seasonal forests,

why does this lynx need
a caterpillar?

Why does the tree need the fish?

And why does this truffle fungus
need one of these?!

Flying squirrel!

Connections like these form
the planet's great ecosystems.

They're vital for all life.

I want to show you our world
as you've never seen it before.

JAUNTY MUSIC

New England in autumn.

There really can't be a more magical
place anywhere on earth,

to appreciate that dramatic
transition between summer
and winter.

But we mustn't get blinded by
this natural fiesta,

because such an extreme
transformation
is a huge challenge for life.

And autumn is just one of many
transformations the forest
must face.

From summer to winter, this land
of plenty will appear to collapse,

before attempting to rebuild itself
all over again in the spring.

To see how, I'm going to, what is
for me, the greatest seasonal
forest on the planet.

The wooded wilderness that stretches
right across North America.

From the land of the Canadian lynx,

to the land of the grizzly bear.

Our story begins in autumn.

As the days are drawing shorter,
less light is feeding the forests.

Deciduous trees are shedding
their leaves.

Many creatures are burrowing away
to escape the cold.

Others are simply leaving.

But there's one animal with
a crucial job to do.

Now, before the winter sets in.

It's a job the entire forest
depends upon.

The best time to see them is in the
first couple of hours after dark.

And what I'm hoping is,
if I stand here and stay really
quiet, I'll be in for a real treat.

It's a creature I've waited
all my life to see.

But they move so fast!

Oh! Did you see that?!

That was amazing, it went
right past my face!

Flying squirrel!

They really are expert gliders.

They can glide for up to 200 metres!

When I was a kid, I was obsessed
with things that were, you know,
not meant to fly.

Flying fish, flying frogs,
flying lizards, flying squirrels.

This is the first time I've ever
seen them.

It was worth a 45-year wait.
Honestly!

Did you... Did you see that?!

I felt it. It went right through
my hair. Seriously!

Centre parting!

It was like a sheet of A4 coming
right over my face

and as soon as they hit the tree
they're running and up they go.

They're just criss-crossing
all the trees.

They immediately scamper up to the
top, then take off and glide again,

and sometimes, I've noticed, they
can even change direction in flight.

Arghh!

One hit me in the chest!

It doesn't come better than that,
does it?

It doesn't get more exciting.

But what on earth have
they got to do with our story?

Well, at the moment, these flying
squirrels are in the woods

trying to find as much food as
possible before the weather turns
nasty and the winter kicks in.

But what are they after?
Well, they're after these.

Truffles.

They're the fruiting bodies of fungi
and they appear in the damp cool
of autumn.

In preparation for winter,

the hungry squirrel needs
to hoard food such as truffles.

But the truffles also need
the squirrel to eat them.

As the squirrel moves through the
forest, the spores are dispersed.

And that's crucial, not just
for the truffle, but for the trees.

What's so special about these
truffles?

They certainly don't look much,
and the smell can be
said to be an acquired taste.

And they're not just here as another
organism to be eaten by hordes
of hungry squirrels either,

because without these truffles,
and all the other fungi here
in the wood,

this woodland simply couldn't
function. It couldn't exist.

Why?

Well, take a look beneath
the soil down here.

Each truffle has thread-like roots
extending from it.

The threads extract nutrients
in the soil,
from rotting material like leaves.

And, cunningly,
they also tap into the roots
of the trees to siphon off sugars.

But this is not a one-way
relationship,

because the tree can now
tap into the nutrients
extracted by the fungal threads.

This symbiotic relationship between
the trees and the fungus,

where each is dependent on
the other,

clearly helps the tree grow,
but it's not only that.

It greatly extends
the reach of its roots

because, in effect, they
become as extensive as the fungal
network that they're connected to.

In autumn, throughout the northern
hemisphere, trees use fungi to
extend their roots

and absorb sufficient
nutrients for the big freeze ahead.

I love this web of relationships -
the squirrels, the fungi, the trees.

It ensures that they're all ready
to face the winter.

But for me, one of the most magical
relationships of all is seen
on the far west coast of Canada,

as one of the world's
most ancient forests

prepares for
the oncoming challenge.

Here, I can stand at the foot of
1,000-year-old cedars

and 90-metre-tall
Sitka spruce trees.

The combination of large mountains

and ocean winds generates
unusually heavy rainfall -

earning this place the title
The Raincoast.

There's so much rain in autumn
that the rivers swollen.

And that is vital to
the forest's survival.

There's a significant event
happening here,

which allows the whole forest
not only to survive the winter,

but also to flourish throughout
the course of the year.

But you know, the really incredible
thing is this key to life

is not here in the forest at all
at the moment, but it will be soon.

After years at sea,
salmon are returning to spawn

in the same forest streams
in which they were hatched.

The swollen rivers make it easy for
them to swim deep into the forest.

But the scent of home also draws
them irresistibly towards danger.

Predators make the most
of this banquet of seafood.

But none of them compare to the most
formidable fish eater of all.

Grizzly bears. Just look at this -
there's a female here,

about 40 metres in front of me,
in the shallows, fishing for salmon.

Behind her, on the bar over there,
she's got three cubs.

They're not struggling
to catch the fish here.

There's such a tremendous surfeit
of tired salmon out there.

All she really has to do is
wander into those shallows

until one comes close.

And then she can grab it,
much to the delight of her cubs.

For these cubs,
it's the first salmon run.

They've got to learn how to catch
fish by watching their mother.

Look at this! Look!

This is the adult grizzly,

that's just leapt off
the island there,

and caught a salmon.
Look at that! Right in its mouth.

Over just six weeks in autumn,

tens of millions of salmon
are going to return to these rivers.

And during the course of a day

one adult bear like this
can eat 40kg of salmon,

and during the course
of a salmon run 1400kg -

that's just one bear's intake.

But every salmon
caught by these bears

increases their chances of survival.

They are incredibly
important to these bears,

particularly at this time of year,

when it's essential that they
bulk up as quickly as possible

before they slip into hibernation
with the winter coming.

This cub hasn't quite got
the hang of it yet,

but he hasn't got long -

the salmon run has only got
a couple of weeks to go.

Until they learn,
Mum has to work even harder.

Every salmon caught
makes a real difference.

These bears, those that are close
to a huge amount of salmon,

grow 80% larger than
those in other areas.

They have 25% more cubs,

and occur at densities
50 times greater.

So salmon, frankly,
are great news for bears.

Exciting as it is to watch,

there's a lot more going on here

than simply bears catching fish.

And the reason is thanks to
what happens next.

And the only way to see it is with
remote cameras,

positioned deep in the forest.

These younger bears have carried
fish 30m from the river.

Because here they are less likely
to be challenged by hungry adults.

So they can eat in peace.

There's so much fish available,
they just eat the richest bits

to lay down enough fat
for hibernation.

The rest appears to be wasted,
abandoned on the forest floor!

Along with our camera.

The aftermath of this feast
is unbelievable.

Up to four tonnes of carcasses
are left in an area the size

of a football pitch.

But what have dead fish

got to do with the forest
preparing for winter?

Well, this is where it starts
to get really intriguing,

because the catching of the salmon
is just the start of it.

Bears aren't the only creatures

attracted by such a feast.

A banana slug.

At 25cm long, it's one of the
largest slugs in the world.

And masses of insects.

These flies
won't survive the winter,

but if they plant their eggs
in the salmon's flesh,

their offspring might.

This flurry of activity

eventually breaks the flesh down
into simple nutrients

that are absorbed into the soil.

The significance of all
of this decaying fish

goes far beyond it being just
a feast for scavengers.

Without all of these rotting salmon
accumulating here every autumn,

this forest would be
a very different place.

The salmon nutrients in the soil
are taken up by the fungi.

So this ancient forest
is better equipped to face

the almighty change
that's fast approaching.

For forests in the Northern
Hemisphere, time has run out.

Every day the sun sinks
lower in the sky.

Winter.

And on the face of it,

all of the life here seems
to have just gone away.

Those truffles and the seeds,

they're locked away underneath
all of this snow.

The salmon run is over.

The vegetation... look at it.
It appears to have shut down.

Even the water is in short supply -
it's all frozen.

All of those connections
appear to be broken.

The fungi have reduced
their recycling to a bare minimum.

And the trees they're connected to
are producing little in return.

The deciduous trees pre-empted
the winter by shedding their leaves.

The conifers are slowing down, too.

The waxy coating on the needles
protects their leaves from the cold.

But not everything here can

exist in a state
of suspended animation.

Some of the animals have to
remain active,

and surviving in conditions
like this isn't easy.

The icy cold
is the cue for the bears

to leave the forest altogether.

With the salmon run over,

they are retreating to their
winter dens, up in the mountains.

They must spend the entire winter
living off their fat reserves

gained by feeding on
all of those salmon.

The squirrels,

and other small mammals,
must keep activity to a minimum,

only occasionally venturing out
to retrieve their autumn caches.

The lower the temperature falls,

the more vulnerable
creatures become.

Winter has been too brutal for this
young white-tailed deer,

but at least it's an opportunity
for some nocturnal scavengers.

A racoon.

Out of the forest, a fisher -
a relative of martens and weasels.

And it's smart enough
to keep this meal to itself!

But there is more to this
lifeless-looking forest

than just the scavengers.

For most creatures, winter is
a brutal and unforgiving time.

But others actually
thrive in these conditions.

You see, for animals
that are adapted to live in winter,

this stripped-down forest ecosystem,

well, it's a wonderland.

In winter, here, there are beautiful
connections,

between some of the forest's most
enchanting characters.

There is one predator here,

an incredibly important animal

that has no intention of avoiding
the snow,

because, unlike me,
it's perfectly adapted to it.

But it's an enigma,
a really, really shy animal,

one that's difficult to study.

Having said that,

scientists have been tracking them
through the forest here

for more than a decade.

Scientists from the Maine Department
of Fisheries and Wildlife

have set a trap to catch one alive.

With those distinctly pointed ears,
it can only be a Canadian lynx.

Lynx are the world's
most northerly-dwelling cats.

And this particular lynx
is well-known

to chief scientist Jen Vashon.

The ear tags are blue with white.

That indicates it's L1-11.

He's called L1-11 and was born
in May 2004.

They've discovered that he is just
one of hundreds of lynx living here.

It's too early
with everybody right there.

In fact, there are more lynx
living in these Eastern forests

than anywhere else in North America.

Now, the fact that L1-11
has lived all of his life

in this frozen forest

has to mean that this is a perfect
place for a lynx to live.

But how can a top predator like this

survive in such
a stripped-down environment,

when there appears to be
so little else here?

The tracks of their prey
are everywhere,

but actually finding one
is a real challenge

because its winter camouflage
is perfect.

It's taken some finding,
but it's there - the snowshoe hare!

You can just make out its beady
little black eye,

and the black tips to its ears.

And these things
form 80% of a lynx's diet.

But, as you can see, they don't
make it easy for that lynx.

Their camouflage is astonishing.

In the summertime they're brown,

but in the winter they moult through
to a white coat.

But they also use this thick brush.

It provides them
with excellent cover

to hide from the lynx, also hide
from the elements,

but it's also crucial
in keeping them alive,

because they climb on top
of the snow and nibble at

all of the shoots and the bark
growing from all of this brush.

Look at that! Beautiful,
and with those big snowshoe feet,

it just sort of floats across
the surface of the snow.

But what the snowshoe hare needs
most to survive the winter

is a specific type of vegetation.

It must be the right height to eat,

and provide enough cover
to hide from all those lynx.

So, the vegetation, here,
must be perfect.

And the reason that it does grow
into this perfect environment,

well, you could never guess.

The most beautiful
thing about this story

is that the lynx, the hare,

patches of cover like this amongst
the forest, didn't happen by chance.

They're all controlled
by the most unlikely of creatures,

a tiny thing, less than
the size of one of my fingernails.

And at the moment it's hiding,

having burrowed into the bark of one
of these trees,

or perhaps in a crack in a log lying
on the forest floor,

covered with frozen snow.

But it's there, and it's waiting.

It's waiting for springtime.

As the hours of daylight increase
and the ground thaws,

as if by magic, the northern forests
change again.

As new leaves appear,
trees start producing sugars,

and that's good for the fungus
in the soil.

Entwined with the trees' roots, they
can siphon off some of these sugars.

But not everything appears
so harmonious.

In the land of the lynx,

something extraordinary
is happening to the forest.

These trees may have endured
the winter,

but now it's spring,
they're under attack.

Some are even dying.

But what's happening here
now is vital

for how this ecosystem
functions over the year.

This defoliation
is entirely natural.

And I might be able to find
one of the culprits down here,

although they're quite tricky
to spot.

They live in these fresh,
green shoots.

Yes, here we are.

Now, wrapped delicately
in these leaves

is a species that is single-handedly

influencing the ecology
of this entire forest.

Inside this nest is the caterpillar
of the spruce moth. The budworm.

And it hasn't only wrapped itself up
in those leaves

to hide from predators,

because it's eating them as well.

And it doesn't just eat the leaves,

it also eats the buds, the flowers,
and the cones on the tree here.

Up in the canopy,
a tiny budworm caterpillar

has just emerged from hibernation.

It's racing to fatten itself up.

When it's finished on one branch,
it releases a strand of silk,

and abseils down to the next.

It's a risky business being a
juicy, fat caterpillar -

you're in danger of being spied
by all of those birds,

just back from migration.

But the caterpillar has a plan -

it uses its silk

to weave the needles together
and hide in a dense web.

Now, the springtime assault
by these caterpillars

is bad news for the trees.

But for other inhabitants
of these forests,

these caterpillars are heroes.

It's thanks to the behaviour
of this species

that one of North America's most
elusive and charismatic predators -

the Canadian lynx - is enjoying
a bit of a renaissance

in forests like this one.

But the caterpillar lives
all the way up there, in the canopy.

Whilst the cat with the pointed ears
is prowling around down here.

So, how can a humble insect
like this have any impact

on a formidable thing like that?

I bet the lynx never even sees
the caterpillar

throughout the course of its life.

Why does the lynx need
the caterpillar?

The clue is how they affect
the lynx's prey on the forest floor.

For decades, scientists have
studied budworm caterpillars,

and a remarkable pattern
has emerged.

They've discovered

that the population of caterpillars
fluctuates dramatically.

And at the peak of a cycle

there can be tens of thousands
of budworms in a single tree.

And this has devastating
consequences.

Whilst these dramatic natural events
might be a catastrophe

for the established trees,
for anything trying to grow

on the forest floor
they are an absolute bonus.

In here, where it's dark,
there's very little,

very poor diversity - just some
mosses and a few ferns.

But as soon as there's
a break in the canopy

and the sunlight can flood in, well,
look at the difference.

Lots of wild flowers, there's
a young maple coming through here,

mountain ash, and, most importantly
of all, regenerating spruce and fir.

The hares essentially need these
regenerating conifers as shelter.

And of course what's good for
the hares is also good for the lynx.

It's such an elegant connection.

Without the spring emergence
of the hungry caterpillars

to chew holes in a dense canopy,

there wouldn't be enough light
flooding the forest floor.

And, with less light down here,
there would be less growing

for our snowshoe hare
to forage and to hide in,

and then there would be nothing
for L1-11

and all of those hundreds
of other lynx to eat.

And that's why the lynx
needs the caterpillar.

And now it's spring,

there's no better time to see
what the future holds

for the lynx population.

Wildlife biologist Jen
is doing a count.

She has detected a signal
from a radio-collared female.

There she is.

But there might
be something else here.

Safe inside her den, a lynx cub.

He's just a few weeks old.

His eyes aren't even open.

Jen must work fast
before Mum returns.

Thanks to the timing of the budworm
opening the canopy this spring,

there's going to be enough prey for
these lynx to hunt next winter.

Far away to the west, The Raincoast
forest is coming back to life.

Thanks to the richness of the autumn
salmon run,

the bears have survived the winter.

They've now returned to the forest,
looking for something to eat.

They'll survive on vegetation
until the next salmon run.

The emergence of the bears
is a cue for scientists

to conduct a rather risky
experiment.

They need a large, hungry, bear.

It's the only way to measure
the impact of all those salmon

on this ecosystem

and to understand why this vast,

ancient forest has thrived
for so long.

For such a big question,

the methods employed by
senior researcher Chris Darimont

seem a bit curious.

He's equipped with a can full
of old salmon guts,

effusing, probably, the most
disgusting smell known to man.

This is wonderful stuff.

But he hopes the bears
are going to love it.

He's made an aerial lure.

So, the wind will carry this
distinctive perfume

deep into the forest.

Wind, extra boost.

Now they surround the area
with barbed wire.

And it's this

that they hope will collect
what they're so interested in -

a single hair from a visiting bear.

Now the site is prepared,

it's time to set some
remote cameras,

and beat a hasty retreat.

Personally, I'm very happy
to watch from a safe distance -

it's not the smell - some of those
bears are huge!

Look at the size of this bear!

As a trap this is the perfect bait,
it's working brilliantly.

The bears have come in,

and they're snagging themselves
on the wire there.

You can see it vibrating about.
And that's just what we want.

Fresh out of hibernation,

it seems they can't resist this
pile of stinking salmon.

This one's even
rolling around in the stuff now.

No doubt it values the scent -
I'm not sure we would.

The bear's coat has been
growing for nearly a year.

but soon it will be moulted
and lost.

The more bears we can attract,
the better.

Now the coast is clear,

and it's time to retrieve
any fur from the barbed wire.

So, what on earth can a hair tell us
about this forest ecosystem?

Well, hair is made of protein,

sourced from whatever the bear has
been eating over the last year.

And by analyzing this hair,

science can reveal an astonishing
level of detail about a bear's life.

We can learn so much
from a single bear's hair.

So I know, for instance, that this
one has come from a female grizzly.

I know exactly what it's been eating
even on a week-by-week basis,

where that food has come from

and even the impact
on the quality of its life.

So this bear has been getting
most of its protein,

not from the forest around here,

but actually from the deep ocean,
via the salmon.

And we know that throughout
the course of the year

80% of that bear's protein
has come from these salmon.

And that's surprising
because, remember,

they're only available to the bear
for a few weeks during the autumn.

And yet the impact is clearly
lasting all year.

So, how come the bears appear to be
so full of salmon?

Well, back in autumn, we saw
the bears scattering fish carcasses

all around the forest floor.

As the protein in those
rotting salmon broke down,

nitrogen from it
accumulated in the soil.

And this salmon nitrogen

is like fertiliser!

So, in spring,

nutrients all the way from the ocean
gradually appear

in all the vegetation growing here.

Just in time for the hungry bears

to eat as they emerge
from hibernation.

And hungry bears
have huge appetites -

they'll eat a third
of their body weight every day!

So that's why their bodies appear to
contain so much salmon.

But the impact
of this ocean-born nitrogen

extends far beyond bears
and their food.

This particular form of nitrogen

can be found in almost all
of the animals and plants

that appear here in the spring.

These Rufous Hummingbirds have
migrated to the forest to breed.

They're drinking nectar from plants

that have been fertilised
by rotted fish.

So, they'll carry the same
salmon nutrients with them

as they fly through the forest.

Many of the insects pollinating
the plants now

were incubated in that decaying
flesh back in the autumn.

As they themselves are eaten,

the salmon nutrients are spread
even further.

Thanks to the bears,
the insects, and the birds,

this salmon fertiliser is spread
deeper and deeper into the forest -

sometimes as much as 800m
from the river,

and this pulse of nutrients
then allows the organisms

which define the forest itself
to prosper - its trees.

Doctor Tom Reimchen
can measure exactly how much

these vast old trees need the fish.

The secret is to look inside
the tree, by taking a core sample.

Written on it is the entire story
of this 300-year-old tree.

The rings I see are two, three,
even four millimetres,

which continues back

to even the early parts
of the 1800s, late 1700s.

Tom has taken similar samples
from thousands of trees.

An entire forest is lined up
in his lab,

each tree waiting
to tell its own story.

In this seasonal climate, annual
rings are created as the tree grows.

From these rings, he can determine
not just the age of the tree,

but also
the amount of growth in each year.

Some of the rings
are thicker than others,

showing that the tree
has grown more.

Like the bear fur,
each annual ring can be analyzed.

Tom can search for
the same type of nitrogen

that's found in the bear's hairs.

It comes from the ocean

and it's called nitrogen-15.

And the data will tell us just
how much nitrogen in those trees

comes from all those salmon.

I think this
is really exciting.

You see, the annual
growth rings here

show the presence of
the stable isotope Nitrogen-15,

which significantly
comes from the oceans.

It could only have been carried here
by the salmon.

Now look, here is the present,
the bark on the outside of the tree,

so these rings represent
perhaps the last 15 years

and they're very closely
packed together.

But here, back in the 1980s,
the rings are twice as thick.

The trees have been growing twice
as much during the course of a year.

So, perhaps the salmon runs
then were even more productive

than they have been recently.

But that's not the best thing.
Come and have a look at this.

By measuring the abundance of that
nitrogen isotope in this material,

I can tell you that majestic old
giants like this beauty here

are actually composed
of up to 85% material

that's derived from salmon.

Now, when I was a teenager,

I remember learning that I was made
of carbon,

and carbon could only be formed
when stars died.

Effectively I was made of dead stars

and that struck me
as terribly romantic.

But look at this.

This is a forest made of the ocean!

That's why the tree needs the fish.

Without this unlikely-sounding
relationship,

this magnificent ancient forest just
wouldn't be the place it is today.

But there is one more relationship,

crucial to seasonal forests
all around the world,

when it comes to surviving
constant change.

And it's one that
reaches its greatest intensity now,

at the height of summer.

It's the driest time of year,
and the trees need water.

Fortunately,
united with their fungal partners,

the trees have massively
extended their roots.

Fungal threads in the soil
are absorbing water

and passing it to the tree.

But what has only recently been
discovered

is the sheer scale
of these fungal root networks.

A single cubic centimetre
of the soil here

can have a mile of these white
fungal threads running through it.

They're called mycorrhizae.

And, for me,

it's these organisms that are
the real secret of the forest here.

In the lab, the genetic fingerprints

of individual mycorrhizae
have been identified.

By mapping an area 30m across,

it's been discovered

that individual fungi
connect to more than a single tree.

Just one fungus can be joined to 80%
of all of the plants growing here.

And, amazingly, these physical links
enable different species of plants

to exchange nutrients.

Older established plants
are even nurturing

younger weaker ones.

It acts like an underground
welfare system!

These giant webs

connect all of the trees
in this forest,

and keep them, and all of the things
that are dependent upon them, alive.

That's why scientists are calling
this the Wood Wide Web.

It's thanks to this natural
phenomenon, the Wood Wide Web,

that, together, the trees in the
forest ecosystems are resilient -

resilient enough to cope with
the dramatic changes

they encounter every year.

And what's really amazing is how
the web is built.

It's thanks to hungry mammals
like our flying squirrels

that this essential life support
system is effectively maintained.

It's actually fair to say that these
trees wouldn't be standing here,

wouldn't be thriving, unless
a squirrel had eaten a truffle.

And that is fantastic!

It is fantastic.

It's fantastic to think
that what animals do in one season

influences the forest ecosystem
throughout the year.

It's almost as if all of these
stories are choreographed.

The arrival of the salmon
at exactly the right time

to fatten the bears for winter.

Then, the emergence of the lush
green vegetation

fertilised by those salmon

to sustain the bears when they
emerge from hibernation.

The squirrels - foraging
for truffles in the autumn time,

and sowing their spores
throughout the forest

to grow a fungal network

that joins all of the trees and all
of the plants,

and provides them with nutrients.

The budworm - chewing
a hole in springtime in the canopy,

so that in summer, sunlight
floods down to the forest floor

and produces the perfect
hunting habitat for lynx.

It's all in the timings.

And it's this that makes these
temperate forests

such magical places.

If you'd like to know more

about the fascinating web of links
between species,

the Open University

has produced some material
both to inform and inspire you.

For your free copy,

or to find out more about
Open University programmes -

And join me next time,

when I'll be travelling to some of
the world's greatest water habitats.

Subtitles by Red Bee Media Ltd